This invention generally relates to latching mechanisms with locking detents, cams, and pivoting positions to align and secure a first member to a second member, and specifically to a latching mechanism for a printhead carriage assembly.
Point of sale (POS) printers for institutions such as banks have been available for years. For printing, some of these earlier printers have been known to use thermal paper or non-pigmented ribbon inks. More recently, inkjets have found their ways to the POS market with great success. Unlike a typical black ink ribbon which starts out printing dark characters (i.e., high density) and then fades over time, an inkjet printer maintains a consistent print, even until the end.
However, while POS inkjet printers have been manufactured for years by a number manufacturers, including Addmaster, the assignee of the current invention, inkjet cartridges, inkjet pens, or inkjet printheads (herein printheads) are supplied primarily by Hewlett-Packard. Thus, as a practical matter, original equipment manufacturers (OEMs), such as Addmaster, will manufacture their own proprietary printer components with the exception of printheads, wherein they will generally turn to Hewlett-Packard for supply.
But as needs, costs, and/or other factors from time to time change, so too will printhead designs. Whenever this occurs, OEMs face a corresponding need to modify their carriages to accommodate these new designs, whether by Hewlett-Packard or otherwise.
The present invention provides a new and unique apparatus and method for securing a printhead to a carriage (or carrier) that is easy and convenient to use. The preferred embodiment includes a carriage with latching mechanism that has at least one cam and locking tab to position the printhead and to secure same within the carriage.
In one preferred embodiment, the carriage is configured to accept the printhead, move the printhead from a first position to engage a corresponding contact pad on the carriage, and then exert a force along an opposing end to secure it within the carriage in a secured second position. Among several options, this is accomplished by providing a latching mechanism with a back plate having at least one cam to both move the printhead and then firmly secure same to the carriage (by engaging with one of the printhead surfaces).
To ensure a somewhat permanent and locked second position until released, engagement detents are provided. These engagement detents are configured to lock the latching mechanism against the carriage""s housing by providing a grabbing surface, such as tabs or ears, for the latching mechanism to engage with. Once secured, the backplate must be intentionally unlatched by releasing the engagement detents. As further discussed below, two additional tabs are incorporated, which are squeezed together to cause the latching mechanism to disengage from the detents.
Another embodiment of the present is a latching mechanism having spring loaded engagement arms to further force the latching mechanism away from the chute, to provide clearance therein for the replacement printhead.